Stalling help
So to start with simce january ive put 8 pumps in my truck (01 f550 with 6.8 v10) 6 were burnt up due to low voltage. Repaired wiring all was good. The other 2 were due to a failing fuel tank liner. I replaced the tank and went to start the truck and it would start and run for a minute then die. Fuel pressure test shows 20psi then drops off (obviously low) i tried a couple new pumps with no change. (The fuel pump relay, inertia switch and fpr are all new). When it starts if i hit the gas it immediately dies off....does anyone have any ideas? Its not a fuel pump electrical fault as i have good power througgout the crank and start.

 

Sounds to me that 20 psi is too low, I think, KOEO it should be about 35psi??? Running about 28psi??. Thinking liner may have gotten into lines blocking fuel, Mybe put the old FPR back in and see if it runs better? I can't see another pump being bad, but you never know. Did you blow the lines out when you had it all apart?? Do you have a frame mount filter on the truck? maybe blocked.

 

That was the next step to blow the lines out and try another fpr. Just looking for some ideas seeing if maybe a sensor etc would cause the issue. It ran when i drive it into shopto do the tank. The only other thing i did was braze weld the y pipe where it was broken....i guess considering the conditions i was in the muffler could be plugged aswell

 

If you've put in 8 fuel pumps since January you've either run into a bad batch of pumps or the power feeding the pump is not a solid 12 volts or more.

 

Wow strange...You would think if the voltage is low the pump just wouldn't turn. Not burn up..How do you know they are burnt and not full of tank goodies? Pumps don't draw much amperage plus they are cooled in the gas.

Nothing controls fuel pressure except pump and fpreg. no sensors etc.
key on for 3 secs 35 psi approx no start.
Sounds like you have virtually no fuel pressure . It would idle at 20 psi.
Clogged filter? FPR prob fine as fuel has to go through filter to get to it.
Maybe jumper relay to have pump run full time and check pressure. Make sure gauge works as its supposed to.

Another thing you could do is disconnect fuel filter inlet and turn on pump to see if you are getting a full line of fuel being careful..you could also do the outlet.

Muffler clogged? get the pressure right before you start thinking elsewhere.